Setup FilOz-owned mainnet monitors

[BigLep]

Context

An action item from filecoin-project/lotus#12467 is to ensure FilOz has some of its own monitors about network health so as members of network stewardship we're not fully dependent on other monitors. This is extra monitoring, not a replacement for the monitoring that Starboard provides.

Per 2024-09-17 team meeting, @jennijuju is going to dump some initial ideas.